Refrigerating apparatus



REFRIGERATING APPARATUS Original Filed Dec. 50, 1931 2 Sheets-Sheet l N Vii/V 7 OR WMMJWZLQ Sept. 13, 1938. C F KETTERING 2,130,092

REFRIGERATING APPARATUS Original Filed Dec. 30, 1931 2 Sheets-Sheet 2 Patented Sept. 13, 1938 REFBIGERATHQG APPARATUS Charles F. Kettering, Dayton, Ohio, assignonby mesne assignments, to General Mo torsCorpo ration, a corporation of Delaware Application December 30, 1931, Serial No.v 583,878

Renewed April 28, 1937 6Claims.

This invention relates to refrigeratingapparatus and more particularly to automation. controlled 'air conditioning apparatus. a

The popularity of automatically controlled air conditioning has increased rapidly in recent years and the use of apparatus therefor in new and different situations has increased rapidly. The growth of this new industry has beenretarded by the relatively high cost of suchtapparatus.

The growth of the industry has also been retarded by the lack of a simplified portable and highly efficient air conditioning apparatus for lowering the relative humidity, particularly in damp places and drying rooms.

Consequently the objects of my invention include the provision of an improved, simpliiied, portable, and highly efficient air conditioning apparatus having a simple automatic control mechanism which can be manufactured and sold at a low cost. a

A more specific object of my invention is to provide an improved electrical humidity control mechanism for dehumidifying apparatus employing a Wheatstone bridge circuit and wet and dry 25 bulb resistance thermometers in the arms of the bridge circuit. I

Another object of my invention is to provide a refrigerating apparatus for lowering the relative humidity of the room in which apparatus the air after being cooled and dehumidiiled by the evaporator is passed directly over the air cooled condenser and compressor for cooling the compressed refrigerant to a greater degree, making the apparatus more efllcient, and also lowering the rela- 35 tive humidity of the air in the room by the heat which is removed from the condenser and the compressor by the circulating air. 7, l a

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings; wherein a preferred form of the present invention is clearly shown.

In the drawings: I r Fig. 1 is a diagrammatic view of an air conditioning apparatus of the compression type together with my improved humidity control apparatus; Fig. 2 is a plan view of my improved portable, dehumidifying apparatus including the humidity 50 control apparatus; and v a a I Fig. 3 is an elevational view of my improved portable dehumidifying apparatus. I

In Fig. 1 I have shown for the purpose of illustrating my invention an air conditioning ap- 55 paratus of the compression type including a compressor 20 for compressing the refrigerant and for forwarding the compressedv refrigerant to a conthe compressor. through the return conduit 28.1

The compressor 20 is driven by a suitable electric motor2'l through pulley and beltmeans 28. The

evaporator is preferably positioned-within the room to be conditioned or in communication with the room or place tobe conditioned.- l

The refrigerant liquefying apparatus, comprising a compressor,.a-motor for driving the compressor, and a condenser may beplaced in the room to be conditioned or it may be placed outside of-the room to be conditioned and con- 20 nected .to the evaporator through the supply and return conduits 23 and ,25. For the purpose of increasing the amount of .air passing over the heat, transfer surfaces of the evaporator 25' a fan driven by'an electric motor 3i provided 2 within a duct 32 is employed for blowing a stream of air over the-evaporator 25. The evaporator 25 cools the air, and if desired will dehumidify the air by cooling the air below its dew point, causing moisture to; collect upon the evaporator 30 25 and to run down the surfaces of the evaporator 25 and collect in the. catch pan 33, from which the condensed moisture will pass through a conduit 34 to a cup 55, which'is kept supplied with water thereby, and 'fromwhich point the 35 excess is conducted to drain through the con- An improved electrical control apparatus is provided for controlling the operation of this air conditioning apparatus. This control apparatus 40 is applicable to any formof apparatus which changes'the amount of humidity in air or any other gas. In this electrical control apparatus there is provided a Wheatstone bridge circuit generally. designated by the reference character 40 having a dry electrical resistance thermometer-4 i,

preferably non-inductively wound, in one of the arms of the bridge circuit, a wet resistance thermometer in another arm of the bridge circuit, and adjustable resistances 43 and in the other arms of the-bridge circuit. The wet, resistance thermometer 42-as well as' the adjustable resistances 43 and 44 are also preferably non-inductively wound so that alternating current, if

desired, may be used ,Iorenergizing the Wheatill stone bridge circuit. The bridge circuit is supplied with electric current by the electric conductors 48 and 49 which are connected to both ends of the bridge circuit, the conductor 48 being connectedbetween the wet and dry resistance thermometers 42 and 4| while the conductor 49 is connected between the adjustable-resistances 43 and 44. These electric conductors 4 8 and 48 may be supplied with directcurrent or with alternating current of a suitable voltage. If desired, alternating current supplied from a transformer connected to the main circuit or any suitable source of alternating current may be used for supplying the current necessary for the useof the Wheatstone bridge circuit.

The wet resistance thermometer 42 is provided with a stockinet covering its surface and a wick' 46 which dips into the water within the cup 35 and supplies moisture to the stockinet 45. Both the wet resistance thermometer 42 and the dry ,resistance thermometer 4| are placed within the duct means 32 so that'the air which is drawn through the duct by the fan 30 is drawn over the surfaces of these two thermometers before it is blown over the surfaces of the evaporator 25. The dry resistance thermometer 4| will therefore be responsive to the dry bulb thermometer temperature of the air in the place-to be conditioned and the wet resistance thermom eter 42, by reason of the evaporation of moisture in the stockinet caused by the air passing thereover, will be responsive to the wetbulb temperature of theair in the room or place conditioned. A'norrnally closed relay 41 is connected'to the sides oi -the Wheatstone'bridge circuit between the dry resistance thermometer 4| and the adjustable resistance 43 on one side and between the wet resistance thermometer 42 and the adjustable resistance 44 on the other side.

It is often desirable :to' operate the apparatus so as to maintain the proper relative humidity at different temperatures. This desired relative humidity will dependupon the particular purpose for which the air is to be conditioned. For drying purposes the main object is to obtain as low a humidity as possible if rapiddrying is desired. In textile mills the humidity must'be carefully controlled for proper spinning, weaving and winding. For comfort it is desirable that I the relative humidity should be lower at higher temperatures. My improvedlcontrol mechanism can provide a control having any character desired. V

If it is desired that the relay should close and the apparatus begin to operate when the relative humidity reaches approximately 100%, the wet and ,dry resistance thermometers may be made of substantially the same kind of wire and the resistances 43 and 44 are adjusted to.be sub- I of the dry resistance thermometer 4| and the wet resistance-thermometer 42 will be substantially the same since very little evaporation'will take place from the stockinet. Under these conditions the current flowing through the relay 41 will be at a minimum and the relay contacts will be permitted to move to closed circuitpositiom If it is desired to maintain a certain wet bulb depression of temperature throughout the range has been reached. Under these conditions the resistance 44 will be adjusted to have a lower value than the resistance 43. compiled below it will be seen that a constant wet bulb depression does not give a constant relative humidity.

Percent relative humidity 5 F. de- 10 F. de- 15 F. dewmpamtm prcssion pression pression "F. Percent Percent Percent If it is desired to have a constant relative humidity the dry resistance thermometer 4| and the wet resistance thermometer 42 are made of different materials so that the electrical resistance of the resistance thermometers 42 increases more rapidly with increase intemperature than with electrical resistance of the dry resistance thermometer 4|. For example, such an effect can be obtained by using copper wire in the, wet resistance thermometer 42 and German silver wire in the dry resistance thermometer 4|, since the resistance of copper per ohm per degree centigrade at 20 centigrade increases .0041 ohm while under the same conditions the resistance of German silver increases only .00036 ohm. This method can also be employed to obtain a lower relative humidity at higher temperature and a higher relative humidity at lower temperatures by properly selecting the materials used in the thermometers. This condition of relative humidity is much more desirable for personal comfort. If desired, however, instead of using such 'a means for compensating for variations in temperature, the relay 41 may be adjusted or provided with a temperature compensating bulb for varying the operation of the relay according to the temperature.

The relay 41 is employed to open and close the relay circuit comprising the conductor 5|, the secondary winding 52 of the transformer 53, the

'relay coil 54 and the electric conductor 55. The

tric conductors 51 and 55 from thepower lines:

The electric conductor 55 is connected to'the relay switch 55, operated by the relay coil 54 and the relay 55, whlch switch connects'at suitable times the electricfconductor 58 with the electric motor 21 througlfthe electric conductor 55' as well as the electric ian mptor 3| through the electric conductor 6|. Theelectric conductor 52 completes the electric circuit of the fan motor 3|. The transformer 53 is provided with a primary winding 63 which is supplied with current from the electric conductor 58. When the relay 41 is closed, the relay 55 closes causing the electric motors 21 and 3| to drive a compressor 20 and fan 30 respectively thus causing the air conditioning apparatus to operate. When the relay 41 opens, the relay 85 will open and stop the opera- From' the table tion of the apparatus. In this way the air conditioning apparatus will be intermittently operated to maintain the desired humidity. f

In damp places and in drying rooms it is usually desired to dehumidify the air without any reference to the temperature of the air. Indeed,

in many cases it is desirable that the tempera fin-type condenser 13 where the refrigerant is,

condensed and forwarded through the conduit 14 to a receiver 15 where this liquefied refrigerant is collected. From the receiver 15 the liquid refrigerant is forwarded through the supply conduit 16 to an expansion valve 11 which controls the flow of liquid refrigerant to the finned evaporator 18 which is situated directly aside of the condenser 13. The condenser and evaporator 13 and 18 are provided with a hood over the top portion. The refrigerant in the evaporator evaporates under reduced pressure and is, returned to the compressor through the return conduit 19. All of the above mentioned apparatus is mounted on the platform 10. An electric motor 80, also supported on the platform, is provided for driving the compressor through pulley and belt means 8|.

The motor and the compressor H are both provided with means for drawing air first through the evaporator and then through the condenser 13 and then over themotor 80 and the compressor ll. adjacent the condenser 13 is provided with fan 83 and the combined pulley and flywheel of the compressor H is provided with fan blades 84 for drawing air first through the evaporator 18, then through the condenser 13, and finally directing the air over the motor 80 and the compressor H. In this way the air is first cooled below its dew point in the evaporator which removes moisture from the air, and then the air passes directly into the condenser 13 which transmits the excess heat of the compressed refrigerant to the air thus condensing the refrigerant and warming the air, and finally the air is discharged over the motor and compressor which also give up heat to the air further warming the air. By warming the air with the condenser, compressor and motor the relative humidity is greatly reduced. The system operates highly efliciently since the condenser 13 is cooled by the relative cold air coming from the evaporator 18.

The apparatus is preferably controlled by the improved electrical control apparatus shown in Fig. 1 and has the Wheatstonebridge circuit including the'wet and dry resistance thermometers and the relay provided within an enclosure 86 having louvers therein for'allowing the air to pass over the wet and dry resistance thermometers on its way to the evaporator 18. This enclosure containing the bridge circuit is preferably placed in the path of the air moving to the evaporator 18. It, however, may be placed in any portion of the room desired, but preferably it should be placed where it will be responsive to the true relative humidity of the room. The primary relay as well as the transformer for the second- For this purpose the motor pulley ary relay circuit are enclosed in the box 81. The

electric current for the motor 80 is supplied through theelectric conductors 88 and 89. The electric current is supplied to the Wheatstone bridge control circuit through the conductors 90 and BI. The electric conductors 92 and 93 conmeet the primary relay housed within the box 8'! and the secondary relay which is housed within the enclosure 86. The electric conductors 9| and 95 conduct electric current from the box 8| to the electric motor 80. g j

With-this type of dehumidiifying apparatus the maximum drying effect is obtained, as well as the maximum efficiency. This is accomplished by reason of the fact .that the air cooled by the evaporator is employed for cooling the condenser, the compressor and the electric motor which raise the temperature of the air without increasing its 'The moisture condensed by humidity content.

7 the evaporator 18 is collected in a catch pan 96- from which it is removed by means of a drain pipe,

or other convenient means- Myimproved con-- trol apparatus so controls its operation of the electric motor 80 so as to prevent the'humidity from rising above the permissible maximum.

Whilethe form of embodiment of the invention as' herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope oi the claims which follow.

What is claimed is as follows:

1. A unitary portable refrigerant dehumidifying apparatus to be placed in a room to be dehumidlfled including commonsupporting means for said apparatus, a refrigerant liquefying apparatus mounted upon said supporting means, said refrigerant liquefying apparatus including a condenser having a plurality of air passages therethrough discharging directly into the room, evaporating means also having a plurality of air passages therethrough discharging directly into the air passages in the condenser and being mounted on said supporting means, saidevaporating means being located aside of and connected to the condenser, and fan means for circulating air from the room to be dehumidifled first through the air passages in said evaporating means to cool the air below its dew point forremoving water vapor therefrom and then through the air passages in the condenser to warm the air to lower charging directly onto the motor and compressor,

said condenser being connected to said compressor, evaporating means operatively connected to said condenser and evaporator, said evaporating means being supported on said supporting means at the side of said condenser, said evaporating means having a plurality of air passages therethrough discharging directly into the air passage in the condenser, and fan means for circulating air from the room to be dehumldifled first over the evaporator to cool the air below its dew point for removing water vapor therefrom and then to'the space to be dehumidiiled.

over the condenser, compressor, and motor to warm the air to lower its relative humidity and to cool and condense the refrigerant passing through the condenser and finally discharging the dc! humidified air into the room to lower the relative humidityof the air therein.

3. A unitary portable dehumidifying apparatus having a common supporting means, a refrigerant 4. A unitary portable dehumidifying apparatus having a common supporting means, a refrigerant evaporating means and a refrigerant condensing means mounted side by side. upon the supporting means, a refrigerant compressing means connected to the condensing and evaporating means and mounted upon the supporting means at the side of the condensing means, and fan means located between the compressing and condensing means for circulating air to be dehumidifled first in heat exchange relation with the evaporating means and then in heat exchange relation with the condensing means. v V g 5. A'unitary portable dehumidifying apparatus having a common supporting means, a refrigerant evaporating means and a refrigerant condensing means mounted side by side upon the supporting means, a refrigerant compressing means connected to the condensing and evaporating means and mounted upon the supporting means-at the side oi the condensing and evaporating means, and means for circulating air to be dehumidined first in heat exchange relation with the evaporating means and then in heat exchange relation with the condensing means.

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